Riko and Jeanne are friends that go back to their time spent in IU. They shared their abilities with each other (Jeanne's knowledge of strategy and Riko's knowledge of disguise) and even loaned each other equipment from time to time. Unlike most students, Jeanne sees Riko for who she really is: Sly, cunning, and very dangerous. It was through Riko that she was able to be smuggled into Academy Island and hunt down Shirayuki.
However, quite a bit of Riko had rubbed off on Jeanne. Though she would never admit it as openly as Riko, Jeanne developed a taste for otaku culture - especially maid outfits - from her time spent with her.
Unlike most girls, Jeanne's interest in Kinji isn't sexual or romantic. She is one of very few characters that fully understand his HSS. Hysteria mode aside, Jeanne and Kinji work very close with each other during missions. As a member of Informa, Jeanne regularly relays information and data to Kinji while he's in the field. There are hints that she has possible repressed feelings for him.
Despite initially trying to kill her, Shirayuki and Jeanne appear to be on very good terms with each other. They've formed a bond, possibly due to their sword skills and choutei status, and regularly rely on each other. When Shirayuki's Irokane Ayame was stolen, Jeanne willingly gave the reforged Durandal to her so she could track down the thief.
Despite being in a lower position in IU than Vlad, Jeanne held little to no respect for the vampire. Her family, along side the first Arsene Lupin, had fought against Vlad to a draw and animosity between the two have remained since. Jeanne felt no qualms in giving Kinji information in how to beat Vlad.
Jeanne and Nakasorachi have known each other before and they are fair friends. They are teammates on Team Constellation.